The antifungal compounds fenarimol, miconazole and dodecylimidazole are selective inhibitors of sterol biosynthesis in fungi. Action of these compounds will be studied in respect to possible binding to sterol carrier proteins in Ustilago maydis. Studies will also involve the nature of inhibition of sterol C-14 demethylation in fungal microsomal systems. Both sensitive and resistant strains of U. maydis will be used. Tricyclazole is a compound which controls certain fungal diseases by a non-fungitoxic mechanism. The compound specifically inhibits polyketide melanin biosynthesis and causes accumulations and deficiencies of certain polyketide metabolites. Studies will be conducted to more fully characterize tricyclazole inhibition in the polyketide pathway of Pyricularia oryzae and to relate this inhibition to the antipathogenic action of the compound.